Ilmatar to begin extensive seabed survey north of Åland

At the beginning of October, Ilmatar Offshore will begin technical investigations of the seabed in the areas of Norrhavet proposed in the Åland Maritime Plan as suitable for offshore wind power. The area is approximately 600 square kilometres and with existing turbine technology the wind farm has the potential for 2.1 GW of power. Connections are planned to the Swedish SE3 area and to Finland.

The Finnish Defence Forces have issued a statement and do not oppose Ilmatar Offshore’s surveys and construction of wind power in the areas. A survey permit from the Government of Åland was granted at the end of August 2022.

“This is an operational takeoff for Ilmatar’s offshore wind venture. The Stormskär and Väderskär wind farms are now formally transferred to development project status with us”, says Anna Häger, Regional Manager of Ilmatar Offshore.

Acoustic survey methods

The seabed surveys are carried out by the Finnish company Arctia on board the vessel Kaiku, a 22.5 metre catamaran with a crew of five working 24/7. The instruments used are multibeam sonar, side-scan sonar, penetrating sonar and seismic boomer.

“Since the surveys are conducted acoustically, i.e. using sound waves, we do not affect the seabed. All instruments operate at relatively high frequencies and low acoustic power and do not cause any damage to marine animals or underwater vegetation,” says Patrik Niskanen, project manager at Arctia.

The results include high-resolution images of the seabed, information on benthic sediments and underlying bedrock, and depth conditions throughout the area.

Environmental and marine biologist Stefan Husa, Ilmatar’s lead expert in marine spatial planning, says the results of the surveys have a major impact on how the project is designed.

“The data we get from Arctia is very detailed and will eventually determine exactly where both the wind farms and the individual turbines can and should be placed to minimise the impact on the marine environment, wildlife and cultural heritage. Without real knowledge of the seabed environment, all forecasts about the potential and design of the wind farms are actually just forecasts. That’s why we start with technical seabed surveys, rather than, for example, analysing existing data or simple sampling. We build our knowledge from the bottom up.”

Funded by Ilmatar

The survey work is funded by Ilmatar and is expected to be completed in early 2023. The analysis of the results will form the basis for further work on Ilmatar Offshore’s environmental impact assessment. The seabed surveys are a significant investment but also mean that Ilmatar is now taking the lead in the work of building large-scale offshore wind power in Åland waters.

“We are the first to carry out this type of thorough, technical analysis of the seabed in Åland waters, and we are doing it despite the fact that the survey licence from the Government of Åland does not guarantee that Ilmatar Offshore can actually build the wind farms. It is costly, for us, but a necessary investment to make a really good and comprehensive environmental impact assessment”, says Anna Häger.